Backing-up blocks from virtual disks in different virtual machine environments having different block lengths to a common data format block length

ABSTRACT

Provided are a computer program product, system, and method for hypervisor agnostic interchangeable backup recovery and file level recovery from virtual disks. Data is stored for a first virtual disk that represents data in a first format and metadata for the first virtual disk in a common data format in a storage having a fixed block length. A virtual disk file represents data in a second format that allows variable size blocks. Multiple instances of the fixed block length of blocks of data for the second virtual disk indicated in the virtual disk file are read. Each instance of the read fixed block length of blocks is written to the storage in the common data format with metadata describing the format of the blocks in the second virtual disk, and can be restored to a third virtual disk in the first or second format.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a computer program product, system, andmethod for hypervisor agnostic interchangeable backup recovery and filelevel recovery from virtual disks.

2. Description of the Related Art

In a virtual machine environment, a hypervisor creates and runs multiplevirtual machines. Virtual machines may access data in one or morevirtual disks, which provide a virtual representation of physicalstorage devices. A backup program may backup the virtual disk. IBM®Tivoli® Storage Manager “(TSM” for Virtual Environments (referred to asData Protection for VMware®) offloads the backup workloads from thesystem hosting the virtual machines to a virtual storage (vStorage)backup server. A Tivoli Storage Manager backup-archive client (installedon the vStorage backup server) may perform complete full, incremental,and incremental forever snapshots of the virtual machines. The TivoliStorage Manager may normalize the storage of the data by storing in aformat independent of the original source data for the virtual disk,known as a common data format.

By normalizing the way that the data is stored and managed, i.e.,storing it in a format that is independent of the original source data,many levels of service can be offered, such as restoring individualfiles from an image of a virtual machine, recovering data thatoriginally resided in a traditional physical environment into a virtualmachine or vice versa, etc. The TSM utilizes a “common data format”which normalizes data from physical volumes and from VMware virtualmachines to realize some of these use cases, especially restoringindividual files from an image of a VMware virtual machine. (TIVOLI andIBM are registered trademarks of International Business MachinesCorporation throughout the world; VMWARE is a registered trademark ofVMWARE Inc. throughout the world)

The TSM system may also reduce the amount of data needed to represent abackup version by utilizing change block tracking (CBT) technology thatprovides only data that has changed between backups to create backupversions. TSM uses the change block tracking mechanism to produce an“incremental forever” backup which only requires that a full backup istaken initially (i.e., all blocks currently used by the virtual machine)and afterwards can rely on incremental backups to represent backupversions. TSM manages the blocks that are incrementally captured toproduce multiple recovery points of the entire virtual machine to theend-user. In summary, backups are optimized through incremental foreverbackup and by storing data in a common data format, the backups can beused either for recovery of an entire virtual machine or for individualfiles.

SUMMARY

Provided are a computer program product, system, and method forhypervisor agnostic interchangeable backup recovery and file levelrecovery from virtual disks. Data is stored for a first virtual diskthat represents data in a first format and metadata for the firstvirtual disk in a common data format in a storage, wherein the commondata format stores blocks of data having a fixed block length. A virtualdisk file representing a second virtual disk is processed, wherein thevirtual disk file represents data in a second format that allowsvariable size blocks, wherein the second format is different from thefirst format used to represent the data for the first virtual disk anddifferent from the common data format. Multiple instances of the fixedblock length of blocks of data for the second virtual disk indicated inthe virtual disk file are read. For each instance of the fixed blocklength of blocks read, the instance of the read fixed block length ofblocks is written to the storage in the common data format with metadatadescribing the format of the blocks in the second virtual disk. Theblocks in the common data format in the storage stored from the firstvirtual disk are restored to a third virtual disk in the first or secondformat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a virtual machine computingenvironment.

FIG. 2 illustrates an embodiment of backup information.

FIG. 3 illustrates an embodiment of a format of a virtual disk file.

FIG. 4 illustrates an embodiment of operations to backup a virtual diskin a first format.

FIG. 5 illustrates an embodiment of operations to backup data from avirtual disk in a second format.

FIG. 6 illustrates an embodiment of operation to restore stored blocksin a backup storage to a virtual disk.

FIG. 7 illustrates a computing environment in which the components ofFIG. 1 may be implemented.

DETAILED DESCRIPTION

The current TSM solutions allow for backing-up of virtual disks in aVMWARE format to a common data format through the use of the changeblock tracking database to track changes to tracks in the virtual disk.One challenge is extending the common data format of TSM to differenttypes of virtual machine environments, such as the Microsoft HYPER-V®virtual machine. (HYPER-V and MICROSOFT are registered trademarks ofMicrosoft Corporation throughout the world). The HYPER-V virtual machinedata is in a variable data format that represents the layout andstructure of data in virtual disk files. However, HYPER-V does notprovide application programming interfaces (APIs) to allow ready accessto the changed block extents from heterogeneous virtual machine backupprograms.

In order to incorporate different types of virtual machine environmentsinto a common data format for storing virtual disk data andincrementally changed data, described embodiments provide techniques forparsing and processing a virtual disk file, such as those files used inthe Microsoft HYPER-V, that allows the layout of the virtual disk to bein variable block sizes. The virtual disk file is processed to readmultiple instances of fixed block length of blocks of data. Multipleinstances of the fixed block length of blocks of data are read for thesecond virtual disk indicated in the virtual disk file. For eachinstance of the fixed block length of blocks read using the virtual diskfile, the instance of the read fixed block length of blocks is writtento the storage in the common data format with metadata describing theformat of the blocks in the second virtual disk. The blocks in thecommon data format backed-up from the second virtual disk may then berestored to a virtual disk in the first format or the second format thatallows for variable sized blocks.

FIG. 1 illustrates an embodiment of a virtual machine computingenvironment 100 having multiple virtual machine (“VM”) environments 102a, 102 b. Each virtual machine environment 102 a, 102 b includes ahypervisor 104 a, 104 b that creates, runs and manages one or morevirtual machines VMs 106 a, 106 b generated in the computing environment100. Each of the VM environments 102 a, 102 b includes one or morevirtual disks 108 a, 108 b that are accessed by one or more of thevirtual machines 106 a, 106 b. The virtual disks 108 a, 108 b provide arepresentation of data that is stored in physical storage devices 110 a,110 b. In one embodiment, the virtual disks 108 a, 108 b use differentformats, such as a first format and second format to represent data inthe virtual disks, such as the case of a VMWARE virtual disk format anda HYPER-V virtual disk format.

In one embodiment, the first VM environment 102 a may utilize ahypervisor 104 a that uses a changed block tracking (“CBT”) mechanism toprovide data in fixed block length blocks to store, which is compatiblewith the common data format, such as VMWARE.

In one embodiment, the second VM environment 102 b may represent thedata stored in the virtual disk 108 b using a parent virtual disk file300 and one or more child virtual disk files 300 ₂ having differentialdata that has changed in response to a user creating an incrementalbackup, such as a snapshot operation at different points-in-time fromwhen the parent virtual disk file 300 ₁ was created. The virtual diskfiles 300 ₁, 300 ₂ indicate a size of the blocks as defined by the userand other metadata on the layout of the blocks in the virtual disk 108b. In one embodiment, the second hypervisor 102 b may comprise theMicrosoft HYPER-V® product and the virtual disk files 300 ₁, 300 ₂ maybe in the virtual hard disk format (“VHDX”) utilized by HYPER-V. Thechild virtual disk files 400 may comprise a differencing virtual harddisk (“AVDX”) used to represent changed data in the virtual diskrepresented by the VHDX file at different points-in-time.

The computing environment 100 may further include a backup manager 120to manage the backing up of the data for the virtual disks 108 a, 108 bin a backup storage 122. The backup manager 120 maintains a backupdatabase 124 having information on the backed-up virtual disks 108 a,108 b. In one embodiment, the backup manager 120 stores data from thevirtual disks 108 a, 108 b in a normalized data format, known as thecommon data format, which stores data in a fixed block length blocks,such as 16 KB.

The backup manager 120 may receive data to backup from the first VMenvironment 102 a in the common data format. In one embodiment, when thefirst virtual disk 108 a is backed-up, after all data in the initialbackup is stored, the further backups are incremental backups of onlychanged data. The first backup environment 102 a, such as the firsthypervisor 104 a may implement an incremental forever backup strategywhere after the initial backup of the data for the virtual disk 108 a,an ongoing sequence of incremental backups occurs where only data thathas changed since a last backup is provided to the backup manager 120 inthe common data format to store in the backup storage 122. The first VMenvironment 102 a may maintain common block tracking technology (CBT) totrack data that has changed.

The computing environment 100 in which the VM environments 102 a, 102 b,virtual disks 108 a, 108 b, and backup manager 120 are implemented maycomprise one or more servers that may communicate over a network, suchas a Storage Area Network (SAN), Local Area Network (LAN), Intranet, theInternet, Wide Area Network (WAN), peer-to-peer network, wirelessnetwork, arbitrated loop network, etc. The storages 110 a, 110 b, and122 may each be implemented in one or more storage devices, or an arrayof storage devices configured as Just a Bunch of Disks (JBOD), DirectAccess Storage Device (DASD), Redundant Array of Independent Disks(RAID) array, virtualization device, tape storage, flash memory, etc.The storage devices in which the storages 110 a, 110 b, 122 areimplemented may comprise hard disk drives, solid state storage device(SSD) comprised of solid state electronics, such as a EEPROM(Electrically Erasable Programmable Read-Only Memory), flash memory,flash disk, Random Access Memory (RAM) drive, storage-class memory(SCM), etc., magnetic storage disk, optical disk, tape, etc.

FIG. 2 illustrates an embodiment of an instance of backup information200 _(i), the backup manager 120 maintains in the backup database 122for each backed-up virtual disk 108 a, 108 b. Each instance of backupinformation 200 _(i), includes a backup identifier (ID) 202 and metadata204 for the backed-up virtual disk 108 a, 108 b, such as file systemstructures, e.g., directories and files, a layout of the blocks on thevirtual disk, point-in-time information of the data. The metadata 204contains sufficient information on the storage structure of the virtualdisk 108 a, 108 b from which the data is backed-up to allow a virtualdisk to be recreated from the data stored in the common data format inthe backup storage 124. The backup information 200 further includesblock information 206 having information on the bocks 206 that arebacked-up in the storage 124 in the common data format,

FIG. 3 illustrates an embodiment of the virtual disk file 300, such asthe virtual disk files 300 ₁, 300 ₂, as including a block allocationtable (“BAT”) 302 that specifies the state and physical file offset foreach block; payload entries 304 indicating whether the payload blockrepresented by a payload entry 304 is present; and sector bitmap blocks306 indicating whether a bitmap is provided for the sector orcorresponding payload block, where the bitmap indicates blocks in thecorresponding payload entry 304 having data. For a child virtual diskfile 300 ₂, the virtual disk file includes information indicating theparent virtual disk file including the data for a previouspoint-in-time, where the indicated parent can comprise the initialparent in the chain or an immediately preceding incremental backup. Fora child virtual disk file providing incremental changes, the sectorbitmap blocks 306 indicate whether a bitmap is provided for a payloadblock, where the bitmap indicates which blocks in the correspondingpayload block 304 have changed data. The virtual disk file 300 furtherincludes metadata 308 indicating further information on the virtualdisk. Further, a sector bitmap for a payload entry 304 may have a valueof one indicating that valid data is present in a payload block, and avalue of zero indicating that data must be read from the parent virtualfile 300 ₁.

FIG. 4 illustrates an embodiment of operations performed by the backupmanager 120 to backup data for a virtual disk 102 a provided in thecommon data format. Upon receiving (at block 400) blocks to backup fromthe virtual disk 108 a in the common data format, the storage manager120 stores (at block 402) the blocks from the virtual disk in thestorage in the common data format (“CDF”). The storage manager 120generates (at block 404) metadata on the blocks being backed-up, such asstructure of the file system and files in the virtual disk 102 a beingbacked-up, virtual disk information, etc, to store in the metadata 204.The blocks provided for the virtual disk 108 a may be from the initialbackup or blocks changed since a previous point-in-time incrementalbackup, such as occurs as part of a snapshot or point-in-time backup.

FIG. 5 illustrates an embodiment of operations performed by the backupmanager 120 to store data for a virtual disk 108 b represented by avirtual disk file 300. Upon initiating (at block 500) an operation tobackup data from a virtual disk 108 b represented by a virtual disk file300, the backup manager 120 generates (at block 502) metadata on theblocks being backed, such as a structure of the file system, virtualdisk information, etc., to store as metadata 204 in the backupinformation 200 _(i) to generate for the virtual disk 108 b beingbacked-up. The backup manager 120 determines (at block 504) a number nfixed block length (e.g., 16 KB) blocks of data required to read all thedata on the virtual disk 108 b. For instance, the backup manager 120 mayprocess the parent 300 ₁ and any child 300 ₂ virtual disk files todetermine the block layout in the virtual disk 108 b, and then determinea mapping of fixed length blocks for the common data format, e.g., 16KB, to the blocks in the second format on the virtual disk 108 b, whichmay be in a variable length from 512 KB to 4096 KB for HYPER-Vimplementations of the virtual disk 102 b. The backup manager 120performs a loop of operations at blocks 506 through 514 for each ofinstance of the n fixed block length blocks of data to read from thevirtual disk 108 b.

At block 508, if there are child virtual disk files 300 ₂ for thevirtual disk 108 b to backup, the backup manager 120 processes thesector block bitmap 306 for the payload entry 304 in the child virtualdisk files 300 ₂ having the fixed block length of blocks to read todetermine whether any child virtual disk files 300 ₂ provide data forthe blocks to read from the virtual disk. For each of the fixed blocklength of blocks to read, the backup manager 120 determines (at block510) the parent 300 ₁ or child 300 ₂ virtual disk file providing a mostrecent version of data for the block. For each of the fixed block lengthof blocks to read, the backup manager 120 uses (at block 512) thedetermined one of the parent 300 ₁ and child 300 ₂ virtual disk files toread the block of the virtual disk. In one embodiment, the backupmanager 120 may issue multiple reads to read blocks of the fixed blocklength using the information from different virtual disk files 300 ₁,300 ₂. After reading the fixed block length of blocks, the backupmanager 120 writes (at block 514) the read data to the backup storage124. Control then proceeds (at block 516) back to block 506 if there arefurther fixed block length of blocks to read from the virtual disk 108b.

In one embodiment, to read the fixed block length of data usingdifferent virtual disk files 300 ₁, 300 ₂, the backup manager 120 mayuses the parent 300 ₁ and one or more child 300 ₂ virtual disk files toaccess the data blocks to read. In a further embodiment, the backupmanager 120 may use a MICROSOFT® WINDOWS® mechanism to present theHYPER-V® virtual disk 102 b as a disk device and make direct reads tothe disk device. In either case, raw data is read from the underlyingsecond physical storage 110 b. (MICROSOFT, HYPER-V, and WINDOWS areregistered trademarks of Microsoft Corporation throughout the world).The backup manager 120 may issue multiple read requests to read blocksidentified in both the parent 300 ₁ and child 300 ₂ virtual disk files.For instance, for a 16 KB read from both child and parent files,assuming a 4096 byte logical block size, the read for the 16 KB fixedblock length block may require two reads: one 12 KB of changed datausing the child AVHDX file 300 ₂ and 4 KB of unchanged data from theparent VHDX file 300 ₁.

The result of the operations of FIG. 5 is the backing-up of a virtualdisk 108 b having data in a variable length format represented in one ormore one or more virtual disk files 300 ₁, 300 ₂ to a fixed block lengthconsistent with a common data format used by the backup manager 120.

FIG. 6 illustrates an embodiment of operations performed by the backupmanager 120 to recover a virtual disk in the second data format, i.e.,the format requiring the use of the virtual disk files 300, from theblocks for a virtual disk stored in the backup storage 122 in the commondata format. The backup manager 120 processes (at block 602) the backupinformation 200 _(i) for the data to restore to determine the layout ofthe data blocks on the virtual disk 102 b to restore. The backup manager120 then determines (at block 604) a mapping of the fixed length datablocks in the storage 122 in the common data format to the layout of theblocks in the virtual disk as indicated in the metadata 204. The layoutof blocks for the virtual disk 102 b to restore may differ from thelayout of the blocks in the backup storage 122, which are in the commondata format. The backup manager 120 reads (at block 606) out the blocksfrom the storage and writes the read blocks to the virtual disk 102 b,which would involve writing the blocks to the second physical storage110 b. The backup manager 120 further generates (at block 608) a virtualdisk file 300 to represent the blocks from the storage written to thenew virtual disk 102 b having the format indicated in the metadata forthe virtual disk.

FIG. 6 is described with respect to recovering a virtual disk in thesecond data format which requires a virtual disk file 300, such as arecovery to a MICROSOFT HYPER-V virtual disk. However, if the user wantsto recover the data for the virtual disk to a format other than HYPER-V,such as a VMWARE compatible format, then the virtual disk file 300 wouldnot be created, and other VMWARE related metadata for the virtual disk102 a being recreated would be generated at block 608.

With the described embodiments of FIG. 6, data backed-up from a virtualdisk 102 a, 102 b in different virtual machine environments 102 a, 102b, e.g., WMWARE, HYPER-V, may be restored to a different virtual diskformat because the data blocks are stored in a normalized form. Thus,data backed-up from a HYPER-V virtual disk, e.g., the second format, maybe restored to a VMWARE virtual disk, e.g., first format, or a HYPER-Vformat, e.g., second format. Likewise, data backed up from a VMWAREvirtual disk, e.g., first format, may be restored to either the VMWAREvirtual disk, e.g., first format, or a HYPER-V virtual disk, e.g.,second format.

Described embodiments provide techniques for backing up and restoringvirtual disks that utilize different virtual disk formats, such asdifferent hypervisors 104 a, 104 b, e.g., VMWARE versus HYPER-V.Although two different hypervisor environments are mentioned, VMWARE andHYPER-V, the described embodiments may be hypervisor product agnosticand used with other virtual machine environments that have differentvirtual disk formats and require conversion to store the data from thevirtual disk in a normalized common data format, such as the CITRIX®XENSERVER® virtualization platform and other virtualization products andplatforms.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Java, Smalltalk, C++ or the like,and conventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The computational components of the computing environment 100, such asthe VM environments 102 a, 102 b, backup manager 120, virtual disks 108a, 108 b and portions thereof may be implemented in one or more computersystems, such as the computer system 702 shown in FIG. 7. Computersystem/server 702 may be described in the general context of computersystem executable instructions, such as program modules, being executedby a computer system. Generally, program modules may include routines,programs, objects, components, logic, data structures, and so on thatperform particular tasks or implement particular abstract data types.Computer system/server 702 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 7, the computer system/server 702 is shown in the formof a general-purpose computing device. The components of computersystem/server 702 may include, but are not limited to, one or moreprocessors or processing units 704, a system memory 706, and a bus 708that couples various system components including system memory 706 toprocessor 704. Bus 708 represents one or more of any of several types ofbus structures, including a memory bus or memory controller, aperipheral bus, an accelerated graphics port, and a processor or localbus using any of a variety of bus architectures. By way of example, andnot limitation, such architectures include Industry StandardArchitecture (ISA) bus, Micro Channel Architecture (MCA) bus, EnhancedISA (EISA) bus, Video Electronics Standards Association (VESA) localbus, and Peripheral Component Interconnects (PCI) bus.

Computer system/server 702 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 702, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 706 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 710 and/or cachememory 712. Computer system/server 702 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 713 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 708 by one or more datamedia interfaces. As will be further depicted and described below,memory 706 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 714, having a set (at least one) of program modules 716,may be stored in memory 706 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. The components of the computer 702 may be implemented asprogram modules 716 which generally carry out the functions and/ormethodologies of embodiments of the invention as described herein. Thesystems of FIG. 1 may be implemented in one or more computer systems702, where if they are implemented in multiple computer systems 702,then the computer systems may communicate over a network.

Computer system/server 702 may also communicate with one or moreexternal devices 718 such as a keyboard, a pointing device, a display720, etc.; one or more devices that enable a user to interact withcomputer system/server 702; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 702 to communicate withone or more other computing devices. Such communication can occur viaInput/Output (I/O) interfaces 722. Still yet, computer system/server 702can communicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 724. As depicted, network adapter 724communicates with the other components of computer system/server 702 viabus 708. It should be understood that although not shown, other hardwareand/or software components may be used in conjunction with computersystem/server 702. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

The terms “an embodiment”, “embodiment”, “embodiments”, “theembodiment”, “the embodiments”, “one or more embodiments”, “someembodiments”, and “one embodiment” mean “one or more (but not all)embodiments of the present invention(s)” unless expressly specifiedotherwise.

The terms “including”, “comprising”, “having” and variations thereofmean “including but not limited to”, unless expressly specifiedotherwise.

The enumerated listing of items does not imply that any or all of theitems are mutually exclusive, unless expressly specified otherwise.

The terms “a”, “an” and “the” mean “one or more”, unless expresslyspecified otherwise.

Devices that are in communication with each other need not be incontinuous communication with each other, unless expressly specifiedotherwise. In addition, devices that are in communication with eachother may communicate directly or indirectly through one or moreintermediaries.

A description of an embodiment with several components in communicationwith each other does not imply that all such components are required. Onthe contrary a variety of optional components are described toillustrate the wide variety of possible embodiments of the presentinvention.

When a single device or article is described herein, it will be readilyapparent that more than one device/article (whether or not theycooperate) may be used in place of a single device/article. Similarly,where more than one device or article is described herein (whether ornot they cooperate), it will be readily apparent that a singledevice/article may be used in place of the more than one device orarticle or a different number of devices/articles may be used instead ofthe shown number of devices or programs. The functionality and/or thefeatures of a device may be alternatively embodied by one or more otherdevices which are not explicitly described as having suchfunctionality/features. Thus, other embodiments of the present inventionneed not include the device itself.

The foregoing description of various embodiments of the invention hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Many modifications and variations are possible in lightof the above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto. The above specification, examples and data provide acomplete description of the manufacture and use of the composition ofthe invention. Since many embodiments of the invention can be madewithout departing from the spirit and scope of the invention, theinvention resides in the claims herein after appended.

What is claimed is:
 1. A computer program product for storing data fromvirtual disks in a backup storage, wherein the computer program productcomprises at least one computer readable storage medium includingprogram instructions, wherein the program instructions when executed bya processor cause operations, the operations comprising: performingincremental backups of a first virtual disk in a first virtual machineenvironment that backs-up only data changed since a last backup to storein a common data format in the backup storage, wherein blocks in thefirst virtual disk in the first virtual machine environment have acommon data format block length of blocks in the common data format inthe backup storage; issuing multiple reads to blocks of data in a secondvirtual disk in a second virtual machine environment having a blocklength that differs from the common data format block length; andwriting the read blocks of data in the second virtual disk to blocks inthe backup storage having the common data format block length to backupthe blocks of data in the second virtual disk.
 2. The computer programproduct of claim 1, wherein the backing up of blocks of data in thesecond virtual disk comprises: for each block of data of the blocks ofdata to backup having the common data format block length, reading datafrom at least one of a parent virtual disk file and child virtual diskfiles having a most current version of data for the block of data,wherein the parent virtual disk file has initial data of the secondvirtual disk and the child virtual disk files have data changed atdifferent points-in-time with respect to the parent virtual disk filefor the second virtual disk.
 3. The computer program product of claim 2,wherein the parent and child virtual disk files have data blocks havinga block length that differs from a block length of the common dataformat.
 4. The computer program product of claim 2, wherein the multiplereads read blocks in the parent virtual disk file and at least one childvirtual disk file to form the block of data to backup.
 5. The computerprogram product of claim 4, wherein the multiple reads for one block ofdata to backup read different block lengths from the parent and the atleast one child virtual disk files, and wherein a sum of the blocks ofdata read in the multiple reads for one block of data to backupcomprises the common data format block length.
 6. The computer programproduct of claim 2, wherein the operations further comprise: determininga mapping of blocks having the common data format block length to blocksin the second virtual disk having a different block length, wherein eachof the blocks to backup having the common data format block length mapto multiple blocks in at least one of the parent and child virtual diskfiles.
 7. The computer program product of claim 1, wherein theoperations further comprise: storing backup information for the secondvirtual disk indicating a layout of blocks in the second virtual diskincluding a block length of the blocks; and using the layout of blocksto restore the blocks in the backup storage from the second virtual diskthat are stored in the common data format block length to the blocklength used in the second virtual disk.
 8. The computer program productof claim 7, wherein the using the layout of blocks to restore the blocksin the backup storage from the second virtual disk comprises:determining a mapping of the blocks in the backup storage having thecommon data format block length to the layout of blocks in the secondvirtual disk as indicated in the layout of blocks in the backupinformation; and reading out the blocks from the backup storage to writeto the second virtual disk.
 9. A system for storing data from virtualdisks including a first virtual disk and a second virtual disk to abackup storage, comprising: a processor; and at least one computerreadable storage medium including program instructions that whenexecuted by the processor cause operations, the operations comprising:performing incremental backups of the first virtual disk in a firstvirtual machine environment that backs-up only data changed since a lastbackup to store in a common data format in the backup storage, whereinblocks in the first virtual disk in the first virtual machineenvironment have a common data format block length of blocks in thecommon data format in the backup storage; issuing multiple reads toblocks of data in a second virtual disk in a second virtual machineenvironment having a block length that differs from the common dataformat block length; and writing the read blocks of data in the secondvirtual disk to blocks in the backup storage having the common dataformat block length to backup the blocks of data in the second virtualdisk.
 10. The system of claim 9, wherein the backing up of blocks ofdata in the second virtual disk comprises: for each block of data of theblocks of data to backup having the common data format block length,reading data from at least one of a parent virtual disk file and childvirtual disk files having a most current version of data for the blockof data, wherein the parent virtual disk file has initial data of thesecond virtual disk and the child virtual disk files have data changedat different points-in-time with respect to the parent virtual disk filefor the second virtual disk.
 11. The system of claim 10, wherein theparent and child virtual disk files have data blocks having a blocklength that differs from a block length of the common data format. 12.The system of claim 10, wherein the multiple reads read blocks in theparent virtual disk file and at least one child virtual disk file toform the block of data to backup.
 13. The system of claim 12, whereinthe multiple reads for one block of data to backup read different blocklengths from the parent and the at least one child virtual disk files,and wherein a sum of the blocks of data read in the multiple reads forone block of data to backup comprises the common data format blocklength.
 14. The system of claim 10, wherein the operations furthercomprise: determining a mapping of blocks having the common data formatblock length to blocks in the second virtual disk having a differentblock length, wherein each of the blocks to backup having the commondata format block length map to multiple blocks in at least one of theparent and child virtual disk files.
 15. The system of claim 9, whereinthe operations further comprise: storing backup information for thesecond virtual disk indicating a layout of blocks in the second virtualdisk including a block length of the blocks; and using the layout ofblocks to restore the blocks in the backup storage from the secondvirtual disk that are stored in the common data format block length tothe block length used in the second virtual disk.
 16. The system ofclaim 15, wherein the using the layout of blocks to restore the blocksin the backup storage from the second virtual disk comprises:determining a mapping of the blocks in the backup storage having thecommon data format block length to the layout of blocks in the secondvirtual disk as indicated in the layout of blocks in the backupinformation; and reading out the blocks from the backup storage to writeto the second virtual disk.
 17. A method for storing data from virtualdisks, comprising: performing incremental backups of a first virtualdisk in a first virtual machine environment in the first virtual machineenvironment that backs-up only data changed since a last backup to storein a common data format in a backup storage, wherein blocks in the firstvirtual disk have a common data format block length of blocks in thecommon data format in the backup storage; issuing multiple reads toblocks of data in a second virtual disk in a second virtual machineenvironment having a block length that differs from the common dataformat block length; and writing the read blocks of data in the secondvirtual disk to blocks in the backup storage having the common dataformat block length to backup the blocks of data in the second virtualdisk.
 18. The method of claim 17, wherein the backing up of blocks ofdata in the second virtual disk comprises: for each block of data of theblocks of data to backup having the common data format block length,reading data from at least one of a parent virtual disk file and childvirtual disk files having a most current version of data for the blockof data, wherein the parent virtual disk file has initial data of thesecond virtual disk and the child virtual disk files have data changedat different points-in-time with respect to the parent virtual disk filefor the second virtual disk.
 19. The method of claim 18, wherein themultiple reads read blocks in the parent virtual disk file and at leastone child virtual disk file to form the block of data to backup.
 20. Themethod of claim 17, wherein the operations further comprise: storingbackup information for the second virtual disk indicating a layout ofblocks in the second virtual disk including a block length of theblocks; and using the layout of blocks to restore the blocks in thebackup storage from the second virtual disk that are stored in thecommon data format block length to the block length used in the secondvirtual disk.